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[ARCHIVED THREAD] - M-16 with unexplainable problems... (Page 1 of 2)
Posted: 10/2/2007 7:53:32 PM EDT
| Goodday all, I just got back not too long ago with a qusetion itching at the back of my mind. When I was oversees, I was issued a 10.5 M-16 as part of the VBSS team I was with. It was probably the most bad-ass weapon I had ever held. I was happier than anything, until it came time to go to the range. The damn thing fired perfectly in semi-auto. As soon as I switched it to full-auto (rock'en roll) it would fire three or four rounds then stop. I would rack it back again pop off a couple more in semi, and as soon as I would switch it over again it would do the same damn thing. Upon inspection I noticed that it was not jamming, it was just barely tapping the primer that's why it wasn't going off in full-auto. I turned it back in finally, and I asked the armory guy what he though. He said "the bolt-carrier is just dirty". That idea didn't sell on me. So, I was wondering what you guy's thought. I mean I did a little bit of research on shorties, how they have gas problems, and all. But this rifle had one of those Noveske Krinkov flash hiders on it. So it couldn't of been that right. Well, just hoping someone can answer that for me it's been kicking my ass for some time now. |
What ship was this on? |
| full-auto, you might want to post your question in the M-16 full-auto section over here M16 forum |
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Sounds like carrier bounce to me, common in "shorties". Carbine is so over gassed that the bolt crashes into the barrel extension and bounces back far enough that it is still in a rearward position when the hammer strikes. I would take the muzzle do dad off and try again, they increase port pressure. Or I would go up one in weight on the buffer. |
If a factory original MK18 they are required to pass acceptance testing as spelled out in MIL-C-71186 (AR), less the endurance test. More then half of the MK18's are not acquired as complete weapons though. |
AAAH Ekie, here I was ready to show my great knowledge of shorties  and you beat me to the punch. What he said is most likely the culprit here, as many short barrels are over-ported to avoid short-stroking, but then this causes the bolt bounce problem. There really is a very fine line when it comes to gas port sizes on shorties, but an over-port problem is fixable with a heavier buffer, while too small of a port requires redrilling the gas port.I guess I could've just typed "+1"... 
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Yes, these are classic symtoms. Try the H buffer too |
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I had the same symptoms when going from a 16" to an 11.5" barrel with a DIAS. I switched to a heavy buffer and end of problem. It's an easy test to swap out buffers, and the cure is immediate. It worked 100% in my case. The original buffer was a standard carbine buffer that came with the DPMS M4gery clone. I got a DPMS "H" buffer from their website for $30 and now it's totally "Rock & Roll". And, I shoot the evil "Wolf" ammo !! |
3 shot burst doesn't cause light primer strikes though, this is caused by the sear not holding the hammer correctly. It lets go prematurely and the hammer rides the firing pin. Sometimes it works as designed, sometimes it doesn't. |
Not KurtVF, but the issue of Small Arms Review in question was January 1998, article titled M16 Shorty Diagnostic on page 12. The article written by Thomas T. Hoel was one of the most informative, well thought out pieces of technical gun writing I have ever read. I kid you not, Mr. Hoel knows his $hit! 
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Could his 'light primer strike' just be a firing pin mark from chambering the round? Edit: I was thinking a burst selector also. |
The gun quits cycling on its own. I'll bet that if you broke it down when it stops (do not eject shell) the hammer will be in the forward position. It happened to mine and almost everyone else's. Mine was fixed with an H buffer and that's all it took. The H buffer slows down the carrier and allows the hammer to behave as designed. |
Exactly. His MK18 SHOULD already have an H buffer. So the answer is going to be to go up to a H2, or ditch the "field modification" that probably induced the malfunction in the first place. |
I didn't know it already had the H buffer. I missed the "field mod" is that the flashhider? |
Yup. One that directly affects the amount of gas redirected to the bolt/carrier assembly and the velocity of the bolt/carrier assembly, too. |
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The correct buffer for the MK18 would be an H3! The H and H2 buffer are for standard M4 and M4 SOCOM HBARs respectively, Commandos get the H3. and that Armorer you spoke of needs to go drive a truck or paint the ship, if the weapon does not function, FIX IT! RMiller |
Provided it hasn't been messed with by a previous owner or a stupid armorer. Full auto parts may have been replaced by "who knows". Could be dirty. Could have wrong parts installed. Burst vs FA. Compare it to another gun like the OPs that works. Gas tube could be bent where it hits the key on the carrier causing drag. Could have worn or broken internal FCG parts. Might not be a MK18 but some cobled together piece of shit. Too many variables. Start by cleaning the piss out of it to include the gas tube. Have the armorer check for damaged, missing or incorrect parts. If the armorer can't identify the problem then have him turn it into 3rd shop for repare and get a ndifferent weapon. |
The H3 is purley a aftermarket product. The H2 is specifically for the RO921HB. |
But its made by Colt for SAW. |
[ARCHIVED THREAD] - M-16 with unexplainable problems... (Page 1 of 2)
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